Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B37/00—Engines characterised by provision of pumps driven at least for part of the time by exhaust
  • F02B37/04—Engines with exhaust drive and other drive of pumps, e.g. with exhaust-driven pump and mechanically-driven second pump
  • F02B37/10—Engines with exhaust drive and other drive of pumps, e.g. with exhaust-driven pump and mechanically-driven second pump at least one pump being alternatively or simultaneously driven by exhaust and other drive, e.g. by pressurised fluid from a reservoir or an engine-driven pump
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B37/00—Engines characterised by provision of pumps driven at least for part of the time by exhaust
  • F02B37/12—Control of the pumps
  • F02B37/14—Control of the alternation between or the operation of exhaust drive and other drive of a pump, e.g. dependent on speed
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B37/00—Engines characterised by provision of pumps driven at least for part of the time by exhaust
  • F02B37/12—Control of the pumps
  • F02B37/16—Control of the pumps by bypassing charging air
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/0002—Controlling intake air
  • F02D41/0007—Controlling intake air for control of turbo-charged or super-charged engines
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D2200/00—Input parameters for engine control
  • F02D2200/02—Input parameters for engine control the parameters being related to the engine
  • F02D2200/04—Engine intake system parameters
  • F02D2200/0406—Intake manifold pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D2200/00—Input parameters for engine control
  • F02D2200/02—Input parameters for engine control the parameters being related to the engine
  • F02D2200/10—Parameters related to the engine output, e.g. engine torque or engine speed
  • F02D2200/101—Engine speed
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/18—Circuit arrangements for generating control signals by measuring intake air flow
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/10—Internal combustion engine [ICE] based vehicles
  • Y02T10/12—Improving ICE efficiencies

Definitions

• the present invention relates to a supercharging system that is applied to an internal combustion engine, and that includes a turbo charger that is powered by the engine exhaust and also an electric supercharger that is powered by
• a system As a supercharging system applied to an internal combustion engine, a system is per se known that comprises both a turbo charger and also an electric supercharger, and with which the response delay of the turbo charger during acceleration is improved by the action of the electrically supercharging (refer to Patent Document #1) .
• Patent Document #1 JP2004 -2512 8 . SUMMARY OF INVENTION TECHNICAL PROBLEM [0004]
• the object of the present invention is to provide a supercharging system that is capable of suppressing the occurrence of hunting along with changeover of the supercharging mode.
• the supercharging system of the present invention is a supercharging system applied to an internal combustion engine, comprising: a turbo charger that is driven by a turbine powered by an exhaust of the engine; an electric supercharger that is electrically powered; a bypass passage that bypasses the electric supercharger and connects an upstream side and a downstream side of the electric supercharger; a bypass valve that is provided for opening and closing the. bypass passage, and that operates between an open position in which it opens the bypass passage and a closed position in which it closes the bypass passage; and a supercharging control device that changes over the supercharging mode between: a single stage
• the threshold values of a parameter that is employed for operating the bypass valve are different between a case of closing operation in which the bypass .valve is operated from the open position to the closed position in order to change over from the single stage supercharging mode to the two stage supercharging mode, and a case of opening operation in which the bypass valve is operated from the closed position to the open position in order to change over from the two stage supercharging mode to the single stage supercharging mode.
• supercharging mode are performed with different threshold values, accordingly, during steady operation or quasi-steady operation, it is possible to suppress the occurrence of hunting, which is caused by frequent opening operation and closing operation of the bypass valve.
• the threshold values for the parameter that is employed for operating the bypass valve may be different between the case of closing operation in which the bypass valve is operated from the open position to the closed position in order to change over from the single stage supercharging mode to the two stage supercharging mode, and the case of opening operation in which the bypass valve is operated from the closed position to the open position in order to change over from the two stage supercharging mode to the single stage supercharging mode, during steady operation or quasi-steady operation in which change over time of an operational state of the internal combustion engine is within a predetermined range.
• the operation of opening the bypass valve and the operation of closing the bypass valve in order to change over the supercharging mode are performed with different threshold values, only during steady operation or during quasi-steady operation. Therefore, during steady operation or quasi-steady operation, it is possible to suppress the occurrence of hunting, which is caused by frequent opening operation and closing operation of the bypass valve. And, in any operational state other than during steady operation or quasi-steady operation, it is possible to employ control that is appropriately adapted to that operational state.
• the parameter may be a rotational speed, an intake air amount, or a boost pressure of the internal combustion engine; and the threshold value for the parameter for implementing the opening operation of the bypass valve may be smaller than the threshold value for the parameter for implementing the closing operation of the bypass valve.
• the two stage supercharging mode is maintained without implementing opening operation of the bypass valve.
• the opening operation of the bypass valve is implemented and transition takes place from the two stage supercharging mode to the single stage supercharging mode . Accordingly, it is possible to suppress the occurrence of hunting, which is caused by frequent opening operation and closing operation of the bypass valve.
• the supercharging control device may implement stopping of electrical driving of the electric supercharger, and also implements the opening operation of the bypass valve. According to this aspect, since it is possible to avoid the two stage supercharging mode continuing between the two threshold values over a long time period, accordingly it is possible to reduce the amount of electrical power consumption entailed by the electrical driving of the electric supercharger.
• a turbine bypass passage that bypasses the turbine of the turbo charger and connects between an upstream side and a downstream side of the turbine
• a wastegate valve that is provided in the turbine bypass passage and is capable of varying its opening amount from a position in which it fully closes the turbine bypass passage and a position in which it fully opens the turbine bypass passage; and in this case, when driving in the two stage supercharging mode is implemented between the threshold value for the parameter for implementing the opening operation of the bypass valve and the threshold value for the parameter for implementing the closing operation of the bypass valve, then the supercharging control device may adjust a boost pressure by operating the wastegate valve. According to this aspect, it is possible to adjust the boost pressure by operating the wastegate valve when driving in the two stage supercharging mode between the two threshold values is implemented.
• a turbine bypass passage that bypasses the turbine of the turbo charger and connects between an upstream side and a downstream side of the turbine
• a wastegate valve that is provided in the turbine bypass passage and is capable of varying its opening amount from a position in which it fully closes the turbine bypass passage and a position in which it fully opens the turbine bypass passage; and in this case, when driving in the two stage supercharging mode is implemented between the threshold value for the parameter for implementing the opening operation of the bypass valve and the threshold value for the parameter for implementing the closing operation of the bypass valve, then the supercharging control device may adjust a boost pressure by operating the electric supercharger, while keeping an operational state of the wastegate valve in the position in which it fully closes the turbine bypass passage.
• the boost pressure by fully closing the turbine bypass passage when driving in the two stage supercharging mode is implemented between the threshold values, it is possible to adjust the boost pressure by operating the electric supercharger, while increasing the allocation of supercharging by the electric
• the supercharging control device increases a rotational speed of the electric supercharger, and, after having operated the wastegate valve towards its open side so that an increase of the boost pressure due to this increase of the rotational speed of the electric supercharger is cancelled, may then simultaneously stop the electrical driving of the electric supercharger and performs opening operation of the bypass valve.
• Fig. 1 is a figure schematically showing the overall structure of an internal combustion engine that is equipped with a supercharging system according to an embodiment of the present invention
• Fig. 2 is an explanatory figure showing a changeover of supercharging mode
• Fig. 3 is a flow chart showing an example of a control routine according to a first embodiment
• Fig. 4 is a timing chart showing an example of control results obtained with this first embodiment
• Fig. 5 is a flow chart showing an example of a control routine according to a second embodiment
• Fig. 6 is a timing chart showing an example of control results obtained with this second embodiment
• Fig. 7 is a flow chart showing an example of a control routine according to a third embodiment.
• Fig. 8 is a timing chart showing an example of control results obtained with this third embodiment. DESCRIPTION OF EMBODIMENTS
• this supercharging system 1 is applied to an internal combustion engine 2.
• This internal combustion engine 2 is built as a spark ignition type internal combustion engine that is mounted to an automobile not shown in the figures and serves as a power source for traveling.
• the supercharging system 1 comprises a turbo charger 3 and an electric supercharger 4, both of which supercharge the internal combustion engine 1.
• the turbo charger 3 comprises a turbine 3a that receives exhaust gas from the internal combustion engine 2 and a compressor 3b that is driven by the turbine 3a.
• the electric supercharger 4 comprises an electric motor 4a and a compressor 4b that is driven by the motor 4a.
• the electric motor 4a is connected to a battery 5, so that electrical power from the battery 5 is employed as power for driving the electric motor 4a.
• the compressor 3b of the turbo charger 3 is provided in an intake passage 6, while its turbine 3a is provided in an exhaust passage 7.
• An intercooler 8 that cools the air pressurized by the compressor 3b and a throttle valve 10 that adjusts the air flow amount are provided in the intake passage 6 at the downstream side of the compressor 3b.
• a pressure sensor 11 that outputs a signal corresponding to the boost pressure (i.e. to the intake pressure) of the internal combustion engine 2 is provided at the downstream side of the throttle valve 10.
• supercharger 4 is provided in the intake passage 6 at the upstream side of the compressor 3b of the turbo charger 3.
• a bypass passage 12 is provided in the intake passage 6, and this passage 12 bypasses the electric supercharger 4 by connecting an upstream side of the electric supercharger 4 to its downstream side.
• a bypass valve 13 for opening and closing the bypass passage 12 is provided in the bypass passage 12. The bypass valve 13 operates between an open position in which it opens the bypass passage 12 and a closed position in which it closes the bypass passage 12. The position where the downstream side of the bypass passage 12 is connected is located between the compressor 4b of the electric supercharger 4 and the compressor 3b of the turbo charger 3.
• the position where the upstream side of the bypass passage 12 is connected is located between the compressor 4b of the electric supercharger 4 and an air flow meter 14.
• the air flow meter 14 is a per se known sensor that outputs a signal corresponding to the magnitude of the flow of intake air.
• a turbine bypass passage 15 that bypasses the turbine 3a of the turbo charger 3 by connecting the upstream side of the turbine 3a to its downstream side, and a wastegate valve 16 that adjusts the flow rate of exhaust flowing through this turbine bypass passage 15, are provided to the supercharging system 1 in order to adjust the boost pressure of the internal combustion engine 2.
• the wastegate valve 16 is of a type that is sometimes termed an active wastegate valve, and is built as an
• elect romagnetically operated valve that is capable of varying its opening amount from a fully closed position in which it fully closes the turbine bypass passage 15 to a fully open position in which it fully opens the turbine bypass passage 15. It is thus possible to vary the flow rate of the exhaust flowing through the turbine bypass passage 15 and the turbine 3a by varying the opening amount of the wastegate valve 16. Since the output of the compressor 3b is varied by doing this, accordingly it is thereby possible to adjust the boost pressure of the internal combustion engine 2.
• An engine control unit (ECU) 20 that is configured as a computer for controlling the internal combustion engine 2 is provided to the supercharging system 1. Apart from controlling various operational parameters of the internal combustion engine 2 in an adequate manner, such as the ignition timing and the fuel injection amount and so on, the ECU 20 also implements control for the supercharging system 1 corresponding to the present invention. Signals from a large number of sensors are inputted to the ECU 20 in order to obtain necessary information for implementing control of various kinds.
• crank angle sensor 21 that outputs a signal corresponding to the rotational speed of the internal combustion engine 2
• SOC sensor 22 that outputs a signal corresponding to the charge ratio of the battery 5 and so on, and the signals from these sensors are inputted to the ECU 20.
• the ECU 20 changes over the supercharging mode of the supercharging system 1 between a single stage supercharging mode and a two stage supercharging mode.
• the supercharging mode is a supercharging mode in which, with the bypass valve 13 in the open position, the turbo charger 3 only supercharges the internal combustion engine 2, due to the electrical driving of the electric supercharger 4 being stopped.
• the two stage supercharging mode is a supercharging mode in which, with the bypass valve 13 in the closed position, the turbo charger 3 and the electric supercharger 4 both supercharge the internal combustion engine, due to the electric supercharger 4 being electrically driven.
• Control adapted to the operational state of the internal combustion engine 2 is employed for changing over between these supercharging modes. For example, during transient operation in which the rate of change of the operational state of the internal combustion engine 2, in other words the rate of change of the engine rotational speed and of the vehicle speed, is greater than a predetermined range, if the deviation between the target boost pressure and the actual boost pressure is greater than a predetermined reference value, then electrical driving of the electric supercharger 4 is implemented in order to supplement the supercharging response delay of the turbo charger 3, so that changeover of the supercharging mode is performed from the single stage supercharging mode to the two stage supercharging mode. Furthermore, the two stage
• the supercharging mode is started from the moment when the accelerator pedal is depressed in the non-supercharging state, and when the pressure approaches the target boost pressure, then changeover of the supercharging mode from the two stage supercharging mode to the single stage supercharging mode is performed.
• the boost pressure is adjusted by feedback controlling the opening amount of the wastegate valve 16 in the direction to reduce the deviation between the target boost pressure and the actual boost pressure.
• changeover of the supercharging mode is implemented on the basis of a supercharging mode changeover map such as, for example, the one shown in Fig. 2.
• the predetermined range for distinguishing between the state of steady or quasi-steady operation and the state of transient operation is set in an appropriate manner according to the characteristics of the internal combustion engine 2.
• Two changeover lines La and Lb are set in the changeover map of Fig. 2, defined by the rotational speed of the internal combustion engine 2 (i.e. by engine rotational speed) and by torque (i.e. by boost pressure) .
• the first of these changeover lines La is used when changing over from the single stage supercharging mode to the two stage supercharging mode.
• the other of these changeover lines Lb is set more toward the low rotational speed low torque (i.e. low boost pressure) side than the changeover line La, and is used when changing over from the two stage supercharging mode to the single stage supercharging mode.
• different threshold values are used for changing over the supercharging mode, depending upon the direction of change of the supercharging mode.
• a certain hysteresis is set in relation to the change of supercharging mode.
• the program of the control routine shown in Fig. 2 is read out from storage by the ECU 20 in a timely manner and is repeatedly executed at predetermined intervals.
• the ECU 20 refers to the signal from the pressure sensor 11, and makes a decision as to whether or not the current boost pressure P is less than or equal PO- , which is a value that is less than a threshold value P0 by a hysteresis amount a.
• P0 is equivalent to a threshold value for implementing closing operation of the bypass valve 13 in order to change over from the single stage supercharging mode to the two stage supercharging mode
• PO-a is equivalent to a threshold value for implementing opening operation of the bypass valve 13 in order to change over from the two stage supercharging- mode to the single stage
• step S2 If the boost pressure P is less than or equal PO-a then the flow of control proceeds to a step S2, whereas if it is not, then the flow of control is transferred to a step S5.
• the ECU 20 controls the bypass valve 13 so as to put it to the open position.
• the ECU 20 controls the boost pressure to a target value by controlling the opening amounts of the throttle valve 10 and of the wastegate valve 16. It should be understood that the target value for the boost pressure is calculated repeatedly in a cycle by a control routine (not shown in the figures) that runs in parallel with the control routine of Fig. 3 on the basis of parameters of the internal combustion engine 2 such as the rotational speed and the load and so on.
• the ECU 20 sets a management flag F for managing the current state of the supercharging mode to "0", which means the single stage supercharging mode.
• the ECU 20 makes a decision as to whether or not the boost pressure P is greater than P0-a and also is smaller than P0. In other words, the ECU makes a decision as to whether or not the boost pressure P is within the hysteresis range (i.e. the neutral zone) . If indeed the boost pressure P is greater than PO-a and also is smaller than P0, then the flow of control proceeds to a step S6, whereas if it is not, in other words if the boost pressure P has reached the threshold value P0, then the flow of control is transferred to a step S9.
• the ECU 20 acquires the intake air amount on the basis of the signal from the air flow meter 14, and, on the basis of this intake air amount, controls the electric supercharger 4 so that it is kept at an idling rotational speed at a level at which there is no intake resistance.
• the ECU 20 controls the opening amount of the wastegate valve 16 to the open side, and thereby adjusts the boost pressure.
• the ECU 20 controls the bypass valve 13 to the closed position.
• the ECU 20 controls the wastegate valve 16 to the fully closed state.
• the ECU 20 controls the boost pressure by operating the electric supercharger 4 as appropriate.
• the ECU 20 sets the management flag F to "1", which means the two stage supercharging mode.
• FIG. 4 An example of the control results provided by the control routine of Fig. 3 will now be explained on the basis of the timing chart shown in Fig. 4.
• the opening amount of the throttle valve 10 becomes almost constant, so that the vehicle is operating in a stationary state or a quasi-stationary state.
• the boost pressure P is raised as the ECU 20 controls the opening amount of the wastegate valve 16 toward the closed side.
• the bypass valve 13 performs closing operation from its open position to its closed position, and is kept at its closed position until the time point t3 (refer to the step S9 of Fig. 3) .
• the timing for starting electrical driving of the electric supercharger 4 is set to be a little earlier than the time point tl at which the boost pressure P arrives at PO .
• the electric supercharger 4 is controlled to an idling rotational speed at a level at which the electric supercharger 4 has no substantial intake resistance (refer to the step S7 of Fig. 3), until the boost pressure P reaches PO- at the time point t3. And at the same time the boost pressure is adjusted by the wastegate valve 16 being operated from fully closed toward the open side (refer to the step S8 of Fig. 3) .
• the bypass valve 13 is operated to open from its closed position to its open position (refer to the step S2 of Fig. 3), and at the same time the electrical driving of the electric
• the closing operation of operating the bypass valve 13 from its open position to its closed position in order to change over the supercharging mode from the single stage supercharging mode to the two stage supercharging mode is performed at the threshold value P0
• the opening operation of operating the bypass valve 13 from its closed position to its open position in order to change over the supercharging mode from the two stage supercharging mode to the single stage supercharging mode is performed at the threshold value PO-a, so that the opening operation and the closing operation for the bypass valve 13 are performed with different threshold values. Due to this, it is possible to suppress the occurrence of hunting, which is caused by frequent opening operation and closing operation of the bypass valve 13 during steady operation or during quasi-steady operation.
• the ECU 20 functions as the "supercharging control device" of the Claims by executing the control routine of Fig. 3.
• the program of the control routine shown in Fig. 5 is read out from storage by the ECU 20 in a timely manner and is repeatedly executed at predetermined intervals.
• the ECU 20 refers to the signal from the pressure sensor 11, and makes a decision as to whether or not the current boost pressure P is less than or equal PO-a, which is a value that is less than a threshold value P0 by a hysteresis amount a. If the boost pressure P is less than or equal PO-a then the flow of control proceeds to a step S22, whereas if it is not then the flow of control is transferred to a step S25.
• the ECU 20 controls the bypass valve 13 so as to put it to the open position.
• the ECU 20 controls the boost pressure to a target value by controlling the opening amounts of the throttle valve 10 and of the wastegate valve 16.
• the ECU 20 sets a management flag F to "0", which means the single stage supercharging mode.
• the ECU 20 makes a decision as to whether or not the boost pressure P is greater than PO-a and also is smaller than P0. If indeed the boost pressure P is greater than PO-a and also is smaller than P0, then the flow of control proceeds to a step S26, whereas if it is not, in other words if the boost pressure P has reached the threshold value P0, then the flow of control is transferred to a step S27.
• step S27 the ECU 20 controls the bypass valve 13 to the closed position.
• step S28 the ECU 20 controls the opening amount of the wastegate valve 16 to the fully closed state.
• step S29 the ECU 20 controls the boost pressure by operating the electric supercharger 4 as appropriate.
• step S30 the ECU 20 sets the management flag F to "1", which means the two stage supercharging mode.
• the timing for starting electrical driving of the electric supercharger 4 is set to be a little earlier than the time point tl at which the boost pressure P arrives at P0.
• the wastegate valve 16 is kept in its fully closed state until the boost pressure P reaches PO-a at the time point t3, and during this interval the boost pressure by the electric supercharger 4 is controlled (refer to the step S29 of Fig. 5) so that the electric supercharger 4 becomes an intake resistance.
• the bypass valve 13 is operated to open from its closed position to its open position (refer to the step S22 of Fig. 5) , and at the same time the electrical driving of the electric supercharger 4 is stopped, so that the supercharging mode transitions from the two stage supercharging mode to the single stage supercharging mode.
• the opening operation and the closing operation of the bypass valve 13 are performed at threshold values that are different from one another, accordingly it is possible to suppress the occurrence of hunting, which is caused by frequent opening and closing operation of the bypass valve 13 during steady operation or during quasi-steady operation.
• control of the electric supercharger 4 was performed so as to keep it at its idling rotational speed
• control of the electric supercharger 4 is not performed so as to keep it at its idling rotational speed; rather, while keeping the wastegate valve 16 in its fully closed state, the electric supercharger 4 is controlled so that it becomes an intake resistance. Due to this, it is possible to keep down the amount of electrical power consumed by driving the electric supercharger 4.
• the ECU 20 functions as the "supercharging control device" of the Claims by executing the control routine of Fig. 5.
• this third embodiment is the same as the first embodiment except for the details of the control, accordingly reference should be made to Fig. 1 for the physical structure of this third embodiment, and the explanation of the first embodiment should be referred to for explanation of that physical structure.
• the program of the control routine shown in Fig. 7 is read out from storage by the ECU 20 in a timely manner and is repeatedly executed at predetermined intervals.
• the ECU 20 refers to the signal from the pressure sensor 11, and makes a decision as to whether or not the current boost pressure P is less than or equal PO-a, which is a value that is less than a threshold value P0 by a hysteresis amount a. If the boost pressure P is less than or equal PO-a then the flow of control proceeds to a step S32, whereas if it is not then the flow of control is transferred to a step S35.
• step S32 the ECU 20 controls the bypass valve 13 so as to put it to the open position.
• step S33 the ECU 20 controls the boost pressure to a target value by controlling the opening amounts of the throttle valve 10 and of the wastegate valve 16.
• step S34 the ECU 20 sets a management flag F to "0", which means the single stage supercharging mode.
• the ECU 20 makes a decision as to whether or not the boost pressure P is greater than PO-a and also is smaller than P0. If indeed the boost pressure P is greater than PO-a and also is smaller than P0, then the flow of control proceeds to a step S36, whereas if it is not, in other words if the boost pressure P has reached the threshold value P0, then the flow of control is transferred to a step S43.
• the ECU 20 acquires the intake air amount on the basis of the signal from the air flow meter 14, and, on the basis of this intake air amount, controls the electric supercharger 4 so that it is kept at an idling rotational speed at a level at which there is no intake resistance. And then in a step S38 the ECU 20 controls the opening amount of the wastegate valve 16 to the open side, and thereby adjusts the boost pressure .
• a step S39 the ECU 20 turns an internal timer ON, and this timer starts to measure time.
• the ECU 20 makes a decision as to whether or not a predetermined time interval has elapsed from when the timer was turned ON, and if this predetermined time interval has elapsed then the flow of control proceeds to a step S41, whereas if it has not yet elapsed then the flow of control is transferred to a step S45.
• this predetermined time interval may be set as appropriate, one preferred method is to acquire the charge ratio of the battery 5 by referring to the signal from the SOC sensor 22, and to set this predetermined time interval to be longer, the higher this charge ratio is. By doing this, it becomes possible to set the time interval according to the level of necessity for reduction of electrical power consumption.
• step S41 the ECU 20 increases the rotational speed of the electric supercharger 4 to a predetermined value.
• step S42 the ECU 20 operates the wastegate valve 16 toward the open side, so as to cancel out the increase of the boost pressure that accompanies this increase of the rotational speed of the electric supercharger 4.
• a step S43 the ECU 20 controls the bypass valve 13 to the closed position.
• the ECU 20 controls the boost pressure by operating the electric supercharger 4 as appropriate
• the ECU 20 sets the management flag F to "1", which means the two stage supercharging mode.
• FIG. 8 An example of the control results provided by the control routine of Fig. 7 will now be explained on the basis of the timing chart shown in Fig. 8.
• the opening amount of the throttle valve 10 i.e. the throttle opening amount
• the boost pressure P is raised by controlling the opening amount of the wastegate valve 16 toward the closed side.
• the bypass valve 13 performs closing operation from its open position to its closed position, and is kept at its closed position until the time point t3 (refer to the step S43 of Fig. 7) .
• the timing for starting electrical driving of the electric supercharger 4 is set to be a little earlier than the time point tl at which the boost pressure P arrives at PO .
• the timer is turned to ON when the boost pressure P reaches the threshold value P0 at the time point t2, after it reverses to decreasing after having exceeded the threshold value P0 at the time point tl (refer to the step S39 of Fig. 7) .
• the predetermined time interval elapses at the time point t3 while the boost pressure remains between the pressures P0 and PO-a, the rotational speed of the electric supercharger 4 increases, and the wastegate valve 16 is controlled toward the open side, so as to cancel out the increase of the boost pressure that accompanies this increase of the rotational speed of the electric supercharger 4.
• the bypass valve 13 is opened from the closed position to the open position
• this third embodiment in a similar manner to the case with the first embodiment, since the opening operation and the closing operation of the bypass valve 13 are performed at threshold values that are different from one another, accordingly it is possible to suppress the occurrence of hunting, which is caused by frequent opening and closing operation of the bypass valve 13 during steady operation or during quasi-steady operation. Moreover, if driving in the two stage supercharging mode with the boost pressure P between P0 and PO-a is continued for more than the predetermined time period, then the system changes over from the two stage supercharging mode to the single stage supercharging mode. Since, due to this, it is possible to avoid driving the electric supercharger 4 continuously over a long time period, accordingly it is possible to keep down the amount of electrical power consumed by driving the electric supercharger 4.
• the ECU 20 functions as the "supercharging control device" of the Claims by executing the control routine of Fig. 7.
• the present invention is not to be considered as being limited to the embodiments described above; it could be implemented in various different ways, provided that the scope of its essential concept is not departed from.
• the boost pressure was employed as the parameter that was used for operating the bypass valve; but it would also be possible to substitute the rotational speed or the air intake amount of the internal combustion engine, instead of the boost pressure.
• Fig. 2 it would also be possible to employ a combination of these physical quantities as this parameter.

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• 2014
  • 2014-06-30 JP JP2014134010A patent/JP2016011641A/ja active Pending
• 2015
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  • 2015-06-29 EP EP15739351.3A patent/EP3161291A1/de not_active Withdrawn
  • 2015-06-29 CN CN201580032870.XA patent/CN106662003A/zh not_active Withdrawn
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